The present invention is generally directed to an apparatus and method for treating Chronic Obstructive Pulmonary Disease (COPD). The present invention is more particularly directed to such an apparatus and method which may be implanted in the human body to expand the thorax and provide additional thoracic volume to support respiratory function.
Chronic Obstructive Pulmonary Disease (COPD) has become a major cause of morbidity and mortality in the United States over the last three decades. COPD is characterized by the presence of airflow obstruction due to chronic bronchitis or emphysema. The airflow obstruction in COPD is due largely to structural abnormalities in the smaller airways. Important causes are inflammation, fibrosis, goblet cell metaplasia , and smooth muscle hypertrophy in terminal bronchioles.
The incidence, prevalence, and health related costs of COPD are on the rise. Mortality due to COPD is also on the rise. In 1991 COPD was the fourth leading cause of death in the United States and had increased 33% since 1979.
COPD affects the patient""s whole life. It has three main symptoms: cough; breathlessness; and wheeze. At first, breathlessness may be noticed when running for a bus, digging in the garden, or walking up hill. Later, it may be noticed when simply walking in the kitchen. Overtime, it may occur with less and less effort until it is present all of the time.
COPD is a progressive disease and currently has no cure. Current treatments for COPD include the prevention of further respiratory damage, pharmacotherapy, and surgery. Each is discussed below.
The prevention of further respiratory damage entails the adoption of a healthy lifestyle. Smoking cessation is believed to be the single most important therapeutic intervention. However, regular exercise and weight control are also important. Patients whose symptoms restrict their daily activities or who otherwise have an impaired quality of life may require a pulmonary rehabilitation program including ventilatory muscle training and breathing retraining. Long term oxygen therapy may also become necessary.
Pharmacotherapy may include bronchodilator therapy to open up the airways as much as possible or inhaled B-agonists. For those patients who respond poorly to the foregoing or who have persistent symptoms, Ipratropium bromide may be indicated. Further, courses of steroids, such as corticosterocds, may be required. Lastly, antibiotics may be required to prevent infections and influenza and pheumococcal vaccines may be routinely administered. Unfortunately, there is no evidence that early, regular use of pharmacotherapy will alter the progression of COPD.
About 40 years ago, it was first postulated that the tethering force that tends to keep the intrathoracic airways open was lost in emphysema and that by surgically removing the most affected parts of the lungs, the force could be partially restored. Although the surgery was deemed promising, the procedure was abandoned.
The lung volume reduction surgery (LVRS) was later revived. In the early 1990""s, hundreds of patients underwent the procedure. However, the procedure has fallen out of favor due to the fact that Medicare stopped remitting for LVRS. Unfortunately, data is relatively scarce and many factors conspire to make what data exists difficult to interpret. The procedure is currently under review in a controlled clinical trial. However, what data does exist tends to indicate that patients benefited from the procedure in terms of an increase in forced expiratory volume, a decrease in total lung capacity, and a significant improvement in lung function, dyspnea, and quality of life.
LVRS is a long and tedious procedure, fraught with potential complications. Infection is always a concern. Further, lung tissue is difficult to suture and seal making leakage a serious potential problem.
Improvements in pulmonary function after LVRS have been attributed to at least four possible mechanisms. These include enhanced elastic recoil, correction of ventilation/perfusion mismatch, improved efficiency of respiratory musculature, and improved right ventricular filling.
While, lung transplantation is also an option, lung transplantation is considered for only those with advanced COPD. Given the limited availability of donor organs, lung transplants are far from being available to all patients.
In view of the foregoing, there is a need in the art for a new and improved therapy for COPD. More specifically, there is a need for such a therapy which could be made available to all COPD patients and which provides more permanent results than pharmacotherapy while being less traumatic than LVRS. The present invention is directed to an apparatus and method which provide such an improved therapy for COPD.
The present invention provides a device and method for treating chronic obstructive pulmonary disease by expanding the thorax of a patient to an expanded condition and maintaining the thorax in the expanded condition. In accordance with one aspect of the present invention, a separator is implanted within the thorax. The separator expands the thorax to the expanded condition. At least one fastener, for example stainless steel suture wire, maintains the separator within the thorax and thereby maintains the expanded condition of the thorax.
In accordance with further aspects of the present invention, the thorax expansion is implemented by an implantable assembly which includes a separator having opposed sidewalls for engaging facing sidewalls of a sternum resulting from surgical sternotomy. The separator has a longitudinal dimension with the opposed sidewalls extending along the longitudinal dimension, and a width dimension, transverse to the longitudinal dimension, separating the opposed sidewalls of the separator and the facing sidewalls of the sternum. As a result, the volume of the thorax is increased and maintained in an expanded condition.
In accordance with further aspects of the present invention, the separator includes a base having a surface extending from each opposed sidewall. The surface extending from each opposed sidewall supports the sternum when the facing sidewalls of the sternum are engaged with the opposed sidewalls of the separator. Preferably, the opposed sidewalls of the separator have a transverse dimension approximately equal to the thickness of the sternum at the facing sidewalls.
The separator is formed of a biocompatible material such as stainless steel or titanium. Alternatively, the separator may be formed of a biocompatible material and include a ceramic covering.